Knife for cutting tire cord fabric



D. W. WARD KNIFE FOR CUTTING TIRE CORD FABRIC May 10, 1966 2 SheetsSheet1 Original Filed June 5.

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INVENTOR DONALD W. WARD Ira ATTORNEY May 10, 1966 D. w. WARD KNIFE FORCUTTING TIRE CORD FABRIC Original Filed June 5 1961 2 Sheets-Sheet 2 w WA E V m DONAL D W. WARD FIG. I2

ATTORNE Y cation of the cutting edge; and

United States Patent 1 Claim. (Cl. 30-140) This is a division ofapplication Serial No. 114,894 filed June 5, 1961.

This invention relates to tubeless pneumatic tires and, moreparticularly, to a method and apparatus for making a fluid-tight splicein the inner plies of such tires.

In the manufacture of tubeless tires, the inside surface of the tire isprovided with a relatively thick layer or liner of rubber-like material,for example, butyl rubber or other elastomer having a high resistance todiffusion of air therethrough. The liner is secured to the insidesurface of the first ply. It has been a serious problem in theemployment of such liners secured to the first ply of tires to make thenecessary splice therein during building of the tire without permittingleakage of air through the splice due to opening of the splice duringshaping or curing of the tire. Heretofore, it has been common practice'to overlap the first cord ply and/or the liner at the spliced area butthis expedient creates a humpacross the entire Width of the tire at thespliced area, which is highly undesirable since it produces an unbalancein the finished tire. Another expedient has been to butt splice thefirst cord ply and/ or the liner, and provide an overlap of gum rubberacross the splice area but this expedient likewise creates a heavy areaacross the spliced area producing an unbalanced finished tire.

The apparatus of this invention consists of a hand tool in the form of aspecially designed knife having the cutting surfaces thereof angularlypositioned so that a beveled cut can be made on a tire reinforcementfabric.

It is the primary object of this invention to provide a tool which iscapable of readily cutting a tire reinforcement fabric ply so that theportion of the ply containing the cords will butt when spliced togetherand the portion of the ply which is the liner will be in a lappedrelationship when spliced together.

A still further object of the present invention is to provide anapparatus for making splices of the character described above The aboveand other objects will be apparent from the following description whenmade in reference to the following drawings, in which:

FIG. 1 is a plan view of a preferred embodiment of the apparatus of thisinvention; I

FIG. 2 is an enlarged sectional view taken along the lines 22 of FIG. 1;

FIG. 3 is a perspective view of the apparatus shown in FIG. 1:

FIG. 4 is a plan view of a length of tire cord fabric and liner beingcut by the apparatus of FIG. 1;

FIG. 5 is a cross-sectional .view with parts broken away, taken alongthe lines 55 of FIG. 4;

FIG. 6 is an enlarged sectional view of the spliced area after the firstply has been applied to a tire building drum;

FIG. 7 is an enlarged sectional view with parts broken away, taken alonglines 7-7 of FIG. 4;

FIGS. 8, 9, and 10 are plan, end, and side views of another modificationof the apparatus of this invention;

FIG. 11 is a view similar to FIG. 2 showing a modifi- FIG. 12 is a viewsimilar to FIG. 6 showing the spliced 3,249,299 Patented May 10, 1966"ice area of the cord fabric which has been cut by the modification ofthe apparatus shown in FIG. 11.

Referring to the drawings in detail and particularly to FIG. 4, a lengthof tire building fabric 10 is shown passing over a roller 11 which ispositioned adjacent to a standard tire building machine, not shown. Thetire fabric web 10 having a thickness of .03 inch comprises a pluralityof parallel cords 12 coated on both'sides with a thin skim coat ofrubber gum 13. A liner or a thick layer of rubber 14 having a thicknessof about .06 inch is disposed across the central portion 15 of thefabric 1% which forms the inner, air impervious surface of the finishedtire.

The tire builder in making a tubeless tire must cut a ply 16 of fabricfrom the web 10 and wrap it around a tire building drum so that theliner 14 engages the drum surface. The ends 17 and 18 are then splicedtogether. In accordance with the usual practice, the tire builder eithertears the marginal portion 19 or pulls one of the cords 12 out of thelayer of rubber 13 to form a guide line XX at the required distance fromthe end 17.

' The tool 20 is used to cut and skive across the central portion 15 ofthe ply in a manner to be described more fully below.

Cutting tool 20 is provided with a handle portion 21 and a body 22having a cutting edge 23, a guide 24, and an enlarged head 25. The head25 is provided with a cylindrical mass of metal which is heated in aconventional electrical oven prior to use to supply heat to the cuttingedge during the cutting operation.

As shown in FIGS. 2 and 3 of the drawings, the cut ting edge 23 extendsat an angle B relative to the plan of the guide 24 which determines theangle of the skive through the liner 14. Preferably, the angle B is lessthan 15 degrees. drawings, the cutting edge 23 and the guide 24 areparallel to each other in plan view and extend at an acute angle to thelongitudinal axis of the body 22.

The tire builder grasps the handle 21 with one hand and holds the edgeportion 19 with his other hand. He then inserts the edge 26 of thefabric inbetween the cutting edge 23 and guide 24 so that the cuttingedge extends transversely across the thickness of the liner 14, with theguide 24 engaging the top surface of the ply 10, and the inboard apexsurface 27 of the body engaging the edge 26 of the fabric. Preferably,the tool is positioned as shown in FIG. 4 with the cutting edge 23 andguide 24 extending at right angles to the edge 26. While holding theknife in this position, the operator moves the cutting tool along theguide line XX transversely of the ply 10 and the cutting edge 23 movesthrough the liner 14 forming coextensive, complementary skive surfaces28 and 29 therethrough. Apex surface 27 is shorter than the thickness ofthe liner 14. As the tool is so moved, the ply edge 26 passes under theguide 24 and over the edge 23 while the ply edge 18 passes under boththe guide 24 and cutting edge 23.

As shown in FIG. 5 of the drawings, a flap of rubber 30 is formed alongthe edge 18 with the sk-ived surface 28 extending at an acute anglethrough the layer of the liner 14. The surface 28 begins immediatelyadjacent the cord 31 and terminates at 32. The surface 29 formed throughliner stock 14 along the edge 26 complements the surface 28 and beginsimmediately adjacent the cord 33 and terminates at 34 which is locatedat least several cords removed from the cord 33.

After cutting a ply 16 from the length of material \10 as describedabove, the tire builder wraps the ply around the tire building drum withthe liner 14 engaging the drum and forms a splice as shown in FIG. 6 ofthe drawings. The surfaces 28 and .29 through the liner 14 are Asfurther shown in FIG. 1 of thecoextensive and parallel and, therefore,form a splice having a length in cross-section substantially greaterthan the thickness of the liner 114, and the cords 31 and 33 arepositioned in the splice area immediately adjacent and parallel to eachother with the splice through the liner 14 extending from a point 35diagonally through the thickness of the liner 14 to a point 36positioned preferably at least several cord-s away from the cords 31 and33. The splice thus formed is exceptionally strong, insuring that thesplice will not open up during shaping or curing of the tire, and at thesame time does not create a heavy spot across the width of the curedtire.

FIGS. 9 through 11 of the drawings show a modification of the apparatusof this invention which cuts ply stock 10 similar to that shown in 'FIG.4 of the drawings to form complementary skive edges 17 and 18 to form asplice as shown in FIG. 6 of the drawings. The modified apparatusdiffers in several respects from the apparatus shown in FIGS. 1 through4 of the drawings, as will be more fully explained hereinafter.

The modified tool 37 is provided with a handle portion 38, and a body39, having a cutting edge 40, a guide 41, and a'resistant heater 42 inthe head 43. Wires 44 and 45 extend through handle 38 and the body 39 tosupply electrical energy to the resistant heater 42. The head 43 isconnected to the handle 38 by means of heat dissipating perforated metalcylinders 46 and 47, each having secured thereto a plate 48 and 49suitably secured together by bolts 50 and insulated from each other bycylindrical insulators 51. As shown in FIG. 8, the guide 41 and cuttingedge 40 extend parallel to each other at an acute angle relative to thelongitudinal axis of the body 39 and as shown in FIG. 9, the cuttingedge 40 extends at a small included angle C, preferably less than 15degrees relative to the upper surface of the head 43.

The tire builder, in a manner similar to that described with respect tothe tool 20 shown in FIGS. 1 through 4, grasps the handle 38 with onehand and holds edge portion 19 with one hand. He then inserts the edge26 of the fabric in between the cutting edge 40 and the guide 41 of thetool 37 so that the cutting edge extends transversely across thethickness of the liner 14, with the guide 41 engaging the top surface ofthe ply 10, and with the surface 52 of the body engaging the edge 26 ofthe fabric. The tool is positioned with the longitudinal axis of thehead 43 parallel to the cords 12. While holding the knife in thisposition, the operator moves the knife along the guide line X-Xtransversely of the ply 10 and the cutting edge moves through the liner14 to form a coextensive, complementary, skive edge 28 and 29therethrough, as shown in FIG. 6. :During the cutting operation, theedge 26 passes under the guide 41 and over the cutting edge 40, Whereasthe ply edge 18 passes under the guide 41 and under the cutting edge 40.

Not only is the tool 37 provided with its ownresistant heater 42 so thatthe cutting edge is continuously heated to the proper temperature duringthe cutting operation, but the angularity of the cutting edge 40 andguide 41 relative to the longitudinal axis of the tool 37 is opposite tothat of the angularity of the cutting edge 23 and guide 24 of the tool20 shown in FIGS. 1 through 4 so that the tool 37 may be moved duringthe cutting operation in a direction parallel to the longitudinal axisthereof.

A further modification of the invention is shown in FIG. 11 of thedrawings in which the tool is identical to that shown in FIG. 1 exceptthat the cutting edge 22a instead of extending at an acute angle B, asshown in FIG. 2 of the drawings, extends in a curvilinear direction withthe inboard portion 22b extending parallel to the guide edge 24 and theoutboard portion 220 extending in a curved direction away from the guideedge 23. The curvilinear cutting edge 220 shown in FIG. 11 of thedrawings makes a cut through the liner 14, as shown in FIG. 12 of thedrawings in which the splice area extends from the point 35a parallel tothe surfaces of the cord fabric for a distance of at least several cordsand then curves through the thickness of the liner .14 to a point 36A sothat the curvilinear surface 29a formed through the liner stock 14 alongthe edge 26a is coextensive with and complements the curvilinear surface28a formed along the edge 18a. It is thus seen that the splice or seamshown in FIG. 12 of the drawings through the liner stock 14 has a lengthin cross-section several times greater than the overall thickness of thecord fabric and substantially longer in cross-section than thecrosssectional length of the splice shown in FIG. 6 of the drawings.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:

An apparatus for cutting rubber coated parallel cord fabric in adirection parallel to' the cord to form a tire ply, said fabric having athin rubber coating on one side and a liner of substantially thickerrubber on the other side comprising, an elongated body having a guide, acutting edge, and means for supplying heat to said cutting edge, saidguide having a beveled edge for engaging the side of said fabric havinga thin rubber coating, said guide edge extending transversely of thelongitudinal axis of said body, said cutting edge containing a bevelcomplementary to the bevel of said guide and extending fromthe'longitudinal axis of said body adjacent'said guide edge, saidcutting edge forming an acute angle with said guide edge, whereby saidcutting edge passes through the liner at an angle transverse of thethickness of said liner to form coextensive complementary surfacesthere-,-

WILLIAM FELDMAN, Primary Examiner.

JAMES L. JONES, JR., Examiner.

